This bike was the result of me needing an excuse to try out the SRAM Automatix 2-speed automatic internal gear hub. Being a fan of the old-school Sturmey Archer 3-speed, this was of particular interest. I had this hub sitting in my ebay watch list for months before finally deciding to get it over with. I then realized that I needed a frame to try this out on, so initially I was going to look for a junky old road bike so the project wouldn't be too much of an investment.
It seemed the aluminum seat post was left in the steel frame for a fairly long time with no grease. It never came out no matter what I tried, so I sent it to my shop of choice to see if they could. No luck. What I ended up doing was chopping off and smoothing out the end of the existing seat post, slitting it at the bolt area, adding a Wald 905 shim, and using a Wald 904 seat post (adapts old Schwinn seat tubes to fit new saddles) in the skinnier tube. That part was not included in the video because it's not usually what someone does while building a bike. I then had to order a second shim because my measurements somehow didn't come out right. So, I have an aluminum seat post, two shims, and a Schwinn adaptor seat post holding the saddle onto the bike. It ain't pretty but it works great.
For running gear, I have a Shimano UN55 bottom bracket, Sugino 170 mm cranks, a 48 tooth Sugino chain ring, and a 22 tooth Sturmey-Archer rear cog. I had heard that the shift point on the SRAM hub was a bit early and there are ways to change that, but it's a "do so at your own risk" kind of thing. Since I am often afraid of working with springs, I decided to just lower the gears to make things easier. I built it up originally with a 21t cog and went for a ride after photographing the bike. It proved to be too tall still, so on went the 22 which was much better. Even top gear was more comfortable. Other things include Shimano RX100 brake calipers, which people said would fit, and Kool Stop Vans brake pads because why not. It turned out that the brake caliper reach was just barely long enough and I ended up swapping in a set of not-as-cool brake pads because the Vans were vertically too thick.
The SRAM Automatix hub is very nice despite the fact, as I mentioned before, that it does indeed shift too early. I'd prefer to be able to spin a little faster while accelerating. The 22t cog helped a lot and since I'm used to bikes much heavier than this, it really wasn't a bother. Anyway, this hub is an actual automatic, not a kick-back. It shifts smoothly and seamlessly. The 2-speed auto essentially has an identical planetary system as a 3-speed with pawls that engage to enable different ratios. Initially, the high gear pawls are retracted, held by spring tension toward the middle of the hub. At 11 mph, there is enough centrifugal force to fling the weighted pawls outward against spring tension, engaging the high gear. For those who are familiar with the Sturmey-Archer AW, think of it like how in 1st gear, the clutch holds the high gear pawls in so they are not driving the hub. Shift to 2nd, and the clutch releases them, allowing them to spring outward and engage the hub shell. It's pretty much the same thing here except the spring tension defaults the pawls to low gear in the SRAM. To downshift, you have to lift off the pedals to let the pawls retract. Adjusting the shift point involves opening the hub and removing the springs, which is the deterring factor for me, and bending them so they have more tension. I assume care must be taken to bend them both by the exact same amount. With more spring tension, the wheel must spin faster in order to shift gears.
I messed up a little in the assembly video and made the brake cables too short, so I didn't have enough slack to wrap them in the bar tape all the way. I had to cut slits to allow them to exit and now it looks messy. Also, somehow, I had a frustrating amount of trouble installing the middle cable clip while the other two went on fine. It's possible that the threads were just a little bit messed up on the end of the clamp bolt.
Also, the bike is named 2Pake obviously in part of what it is, but also couldn't pass up the chance to reference the late, talented rapper 2Pac. Cheesy, I know. The "2" stickers I added are retro-reflective which I think is kind of cool.
Well, as I said in the beginning, I had my fun and
EDIT Sept. 2016: My old roommate, who bought the 1965 Hercules 3-speed and the '76 Varsity, who also owned a newer Pure Fix bike, decided to trade the Schwinn and the fixed-gear for this one. The values worked out and I am glad this bike is staying "in the family."